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Coming dissertations at MedFak

  • Identification and clinical implementation of biomarkers for cervical cancer Author: Malin Berggrund Link: Publication date: 2020-04-16 14:05

    Introduction of organised screening programs and prophylactic vaccination against human papilloma virus (HPV) have successfully reduced the incidence of cervical cancer globally. In Sweden, the incidence has been reduced by about 50 % since the introduction of the national screening programme in the late 1960’s. Despite these efforts, cervical cancer is still a major cause of cancer deaths globally.

    In order to reduce cervical cancer, the screening program should have a high participation rate and be based on a sensitive and specific screening test. About 20 % of women in Sweden do not participate in the organised screening program, and during the last years we have also seen a rise in cervical cancer cases in Sweden among women who participate in the screening program. Thus, there is a need to develop improved screening strategies that result in a higher participation rate, and are based on tests that more precisely identify women with high risk of developing cervical cancer. This includes searching for novel biological markers (biomarkers) that can be used to more accurately identify women with a high risk of developing cervical cancer.

    By offering women self-sampling for HPV analysis through direct mailing of sample kits with a chemically treated paper card, the FTA card, we were able to increase the participation rate in the screening program. We also found that the use of repeated self-sampling for women that were HPV positive in the primary screening sample increased the number of women detected with higher risk of cervical cancer (Paper II). Self-sampling was shown to be non-inferior to assisted sampling by midwife (Paper III). Using this sample collection device, we further investigated the association between increased risk of cervical cancer and HPV viral load (Paper V) as well as the vaginal microbiota (Paper VI). We also showed that proteins in the vaginal fluid can be studied using self-sampling and the FTA card (Paper I). Lastly, we identified plasma proteins that are associated with cervical cancer and could represent future biomarkers (Paper IV).

    This thesis has provided novel aspects on the present screening strategy, explored opportunities to increase the participation rate as well as examined possible future biomarkers for screening of cervical cancer.

  • The Human Vestibular Aqueduct, Endolymphatic Duct and Sac : A Morphological Study Using Micro-CT, Super Resolution Immunohistochemistry and Synchrotron Phase Contrast Imaging Author: Charlotta Kämpfe Nordström Link: Publication date: 2020-04-16 11:29

    The inner ear lies sheltered in the temporal bone and consists of basically three parts: the cochlea (the hearing organ), the vestibular (the balance organ), and the endolymphatic duct (ED) and endolymphatic sac (ES). The ES and ED are located in a bony canal, the vestibular aqueduct (VA), located on the medial side of the vestibule. While the functions of the cochlea and the vestibular part of the inner ear are rather well studied, our knowledge of the function/s of the ES and ED remains limited and has intrigued scientists for centuries. Earlier studies have supported several theories, such as being an immune mediator, an aid in pressure regulation, related to the absorption of endolymph, and the production of endolymph.

     Otologic disorders, which affect both hearing and balance, such as Meniere’s disease (MD) and large vestibular aqueduct syndrome (LVAS), have been linked to dysfunction of the ES/ED. Studies of the human inner ear are fairly sparse. Research on the ES and ED have mainly been performed on animals, although both the anatomy and function may differ among various species.

    This thesis aims to further investigate the anatomy and function of the human ES and ED with the two otologic disorders MD and LVAS in mind. To achieve this, we have used novel imaging techniques, such as super-resolution structured illumination microscopy (SR-SIM), micro-computerized tomography (micro-CT), and synchrotron radiation phase-contrast imaging (SR-PCI). The material used for imaging comes from different sources: human archival temporal bones from the Uppsala temporal bone collection; human fresh-frozen cadaveric bones from our collaborators at Western University, in London, Ontario, Canada; and fresh-frozen human ES harvested during vestibular schwannoma surgery after securing ethical permission.

    The results of these studies describe the micro-anatomy of the VA, ED and ES down to a nanoscopic level. The discussion is based on the findings, relating them to earlier research with clinical implications regarding MD and LVAS.

  • Deciphering Binding Patterns of Therapeutic Antibodies with Immune Cells : From Method Development to Application Author: Sina Bondza Link: Publication date: 2020-04-15 13:56

    Reversible binding, for example between signaling molecules and receptors on the cell surface, is one of the main means to communicate information in cellular systems. Knowledge about how molecules interact is crucial for both understanding biological function and for therapeutic intervention. The cellular environment often makes ligand-receptor interactions complex with the membrane providing structural support and containing other components that interfere with the interaction. One of the fastest growing drug classes for targeting cellular receptors are monoclonal antibodies (mAb), in particular within oncology. Therapeutic mAbs can have direct effects on target cells mediated via the Fab-domain and immune-related effects that are mediated via the Fc-domain. An example of the latter is activation of the complement system by binding of its first component C1q to Fc-domains. Furthermore, immune cells can recognize Fc-domains via Fc-receptors and cause target cell death by a process called antibody-dependent cellular cytotoxicity (ADCC).

    Increased understanding about structure-binding-function relationships facilitates rational drug design, as has been demonstrated with the development of next-generation mAbs that harbor a structural modification on their Fc-domain that strengthens the interaction with immune cells thereby increasing ADCC efficacy. In this thesis, assays for characterizing mAb binding and mAb mediated interactions on live cells were developed and applied to illustrate how detailed knowledge about binding processes helps to understand the relation between binding and biological function.

    Paper I describes a protocol for real-time interaction analysis of antibodies with live immune cells enabling binding measurements in a relevant cellular context with the data resolution needed to study complex binding processes.

    Paper II presents a novel real-time proximity assay that allows to study binding kinetics in connection with receptor dimerization and clustering thereby aiding in decipher complex interactions.

    In paper III, binding patterns of the CD20 mAbs rituximab, ofatumumab and obinituzumab were established on cells revealing that the fraction of bivalently bound mAbs differed resulting in dose-dependent affinities for rituximab and obinituzumab.

    In paper IV, a C1q binding assay to mAb opsonized cells was developed and it was shown that a higher degree of bivalent binding correlated with stronger C1q binding for the CD20 mAbs evaluated in paper III.

    In paper V, an assay to study mAb mediated cell-cell interactions was set-up and it was found that neutrophil engagement with target cells was similar for antibodies of IgG and IgA isotype.